Demand for improved wire grid polarizer (WGP) durability is increasing. For example, a WGP may need to withstand high temperatures, such as for example in newer computer projectors which are progressively becoming smaller and brighter with accompanying higher internal temperature.
Selectively-absorptive WGPs are particularly susceptible to damage due to high temperature because they absorb a large percent of incident light. Such WGPs typically have wires that include a reflective portion (e.g. aluminum) and an absorptive portion (e.g. silicon). The absorptive portion can absorb about 80%-90% of one polarization of light, and thus over 40% of the total amount of light. Much of the heat from this absorbed light conducts to the reflective portion of the wire, which can melt, thus destroying the WGP.
The wires in a visible light WGP can be narrow (about 30 nm) and tall (about 300 nm) and consequently delicate. It is difficult to protect these wires from toppling without degradation of WGP performance.
Oxidation of wires of a WGP can degrade or destroy WGP performance. As with protection from toppling, it is difficult to protect wires from oxidation without the protective mechanism degrading WGP performance.
It is also important to protect wires of the WGP from corrosion. Due to the nanometer-size of the wires, and high performance requirements, even a small amount of corrosion can make the WGP unsatisfactory. It is difficult to provide sufficient corrosion protection without causing performance to drop below minimum standards.